The invention relates to a liquid ring pump having a first housing part which encloses two or more working spaces radially, in which in each case there is arranged an eccentrically rotatably mounted impeller, having second and third housing parts, which seal off the first housing part and the pump on both sides and have ducts or chambers for the supply and discharge of the gas conveyed, and having control disks that bound the working spaces in the axial direction.
In liquid ring pumps, an impeller rotates within an eccentrically circulating liquid ring. During the rotation, the liquid ring penetrates to a greater or lesser extent into the cells formed between the vanes of the impeller. As a result, the free volume in the impeller cells is alternately enlarged and reduced. In that region of the revolution in which the cell volume is enlarged, the suction opening, through which the gas to be conveyed is sucked into the cells, is located at the end in a control disk. In the end region of that part of the revolution in which the compression is carried out, there is the pressure opening, through which the compressed gas in the pressure space of the pump is exhausted.
Liquid ring pumps are employed both as a vacuum pump, where they compress the gas conveyed from a negative pressure to approximately atmospheric pressure, and also as compressors, in which they compress the gas conveyed from atmospheric pressure to a positive pressure. There are liquid ring pumps of single-stage and multistage designs. Single-stage liquid ring pumps can be applied as a vacuum pump in the upper coarse vacuum or as a compressor, on account of the low compression ratio. Multi-stage machines have their preferred range of use as a vacuum pump in the lower pressure range of the vacuum.
The working spaces in which the impeller rotates and in which the liquid ring is built up are bounded axially on one side or on both sides by a control disk. In the case of multistage liquid ring pumps, these working spaces with impeller and control disks are arranged one after another axially in an appropriate number.
Traditionally, a liquid ring pump (cf., for example, DE 27 14 475) comprises a large number of components which are arranged on one another in the axial direction during the pump assembly. The supporting surfaces of the individual components are at the same time sealing surfaces of the machine from the pump interior to the environment. Axially on the outside, the control disks are adjoined by the outer housing, in which ducts or chambers for the guidance of the gas and liquid streams are contained. Surfaces which in turn have to be sealed off are also present between the control disks and the outer housings.
Such a conventional liquid ring pump has, in a two-stage design, seven axial sealing surfaces (DE 27 14 475). Accordingly, the assembly is complicated and the design is expensive and also has the disadvantage of a large number of surfaces which have to be sealed off, in particular a greater risk of developing leaks earlier in operation.
In the case of two-stage liquid ring compressors, a widespread design is provided with a diagonal connecting tube, with which part of the gas to be compressed and of the operating liquid are led on the outside from the pressure opening of the first stage to the suction opening of the second stage (DE-B 870 004). Since this connecting tube is fitted to housing connectors on both sides, there are two further sealing surfaces here. The disadvantages of these classical designs are the large number of individual parts with correspondingly high fabrication costs for the machining of the many surfaces and the many surfaces which have to be sealed off between the pump components.
Many approaches to simplifying pump parts or to fusing a number of pump parts and in this way reducing the number of parts of the liquid ring pumps are already known. For example, it is known to design a control disk with the central element as one component (drawing from Travaini Pumpen TRHC 40-60). A single-stage liquid ring compressor is also known in which the division of the gas streams on the suction side and leading the gas streams together on the pressure side are not carried out outside the compressor by means of what are known as Y tubes; instead, the gas stream is connected only in one side of the housing and the division to the respective other side of the housing is carried out by means of straight tubes (EP 0 584 106 B1). Is also known to accommodate all the actual flow ducts in the central housing part (DE 197 58 340 A1) The disadvantage of this embodiment is that it can be applied only to single-stage liquid ring pumps.
The object of the invention is to provide a liquid ring pump of the type mentioned at the beginning in which the number of individual parts and, in particular, the number of sealing surfaces to the outside is reduced considerably.